The early 15^th century saw the development and widespread use of oil paints in fine arts. Although some version of oil-based paints had been used for painting small details since the 13^th century, they were not used as the main medium for painting until the Renaissance. There are several reasons artists of this period chose to adopt oil paints. The medium that dominated painting prior to the Renaissance was tempera, a mixture of colored pigments and a binding agent such as egg yolk. Tempera paint is permanent and very fast drying, meaning that once the paint was laid down the artist had very little time to alter or improve their work. As Renaissance artists began focusing more on achieving greater realism, they felt limited by the short time frame allowed by tempera paint. This led them to utilize oil paints, which have a much longer drying period that enables the artist to continuously update their work. In addition to this, oil paints have greater variation in the opacity and transparency of the pigments. This characteristic allows the paint to be layered and creates greater depth and more saturation of color. Because of these characteristics, oil paint was the dominant medium of the Renaissance.